1,244 research outputs found
The impact of corporate social responsibility on stock returns: Evidence from the U.S. stock market
Business/Education and Human Ecology/Speech and Hearing Science (The Ohio State University Denman Undergraduate Research Forum)Corporate social responsibility, often abbreviated “CSR,” is a company’s practices and initiatives to take responsibility for the benefit of society. The purpose of this study is to examine the impact of corporate social responsibility on the stock returns of U.S. publicly-traded companies that constitute S&P Composite 1500 Index, based on the stock performances during 2000-2014. Following a disaggregate measure as well as conducting cross-sectional one-year lagged regression analyses, the study assesses the effect of three corporate social responsibility indicators from the KLD STATS database, including: (1) Environmental Performance; (2) Corporate Governance Performance; and (3) Social Performance indicators. All three variables are compared with an aggregated CSR rating score, measured as the KLD indicator. This analysis indicates a significant negative correlation between the overall aggregated CSR rating score and stock returns. Corporate Governance is the only indicator found to be statistically significant and inversely correlated with stock returns. Environmental performance has a stronger, though statistically non-significant, negative impact on stock returns compared to Social and Corporate Governance performance scores. Based on four cross-sectional models, the analyses in this study indicate that taking the CSR initiatives will in fact have negative effect on the stock performance as well as the development of the company.Undergraduate Research OfficeNo embargoAcademic Major: Financ
Total synthesis of ht-13-A and ht-13-B, total synthesis of aurantioclavine, progress towards the synthesis of cycloclavine
Total synthesis of tetracyclic indole alkaloid ht-13-A and ht-13-B has been accomplished from commercially available (S)-4-amino-2-hydroxybutyric acid and trans4-hydroxy-L-proline respectively. The key synthetic steps include an acyliminium ion allylation, a Mitsunobu reaction, a palladium-catalyzed Stille-Kelly cross coupling reaction, and a carbon monoxide mediated palladium-catalyzed reductive Nheterocyclization. The total synthesis of aurantioclavine has been studied. The synthesis commenced with 2-amino-3-nitrophenol. Key synthetic steps include a Stille coupling reaction, a Heck reaction, a Lewis acid mediated cyclization and a carbon monoxide mediated palladium-catalyzed reductive N-heterocyclization. In addition, the first asymmetric total synthesis of (+)-cycloclavine has been studied. Key synthetic steps include a ring closing metathesis, an acyliminium ion allylation and a Stille coupling
Folate Receptor-Targeted Delivery of Small Interfering RNA to Cancer Cells
The vitamin folic acid (folate, FA) has been extensively explored as a targeting ligand to deliver a variety of diagnostic/prognostic/therapeutic agents into various tumors through the assistance of its receptor – the folate receptor (FR). FR is over-expressed in many types of human cancer and can mediate internalization of FA-conjugates through an endocytic pathway. The discovery of small interfering RNA (siRNA), which is cable of inducing potent gene silencing in a sequence-specific manner, provides an excellent molecular tool to suppress aberrant gene expression in malignancies, and therefore siRNA has the potential to revolutionize cancer therapeutics. Towards the goal of developing an efficient and cancer-specific siRNA strategy, three types of FA-conjugated molecules have been synthesized to investigate targeted siRNA delivery to cancer cells in vitro.
In the first section, FA-linked siRNA was synthesized through our one-step in vitro transcription using FA-HAD-AMP as a transcriptional initiator. FR-dependent cellular uptake and moderate specific gene down-regulation (50%) were observed in a stable cell line (Gluc-KB), which was established in this work by integrating Gaussia luciferase (Gluc) gene to the genome of KB cells (human nasopharyngeal carcinoma). Gluc-KB provides a platform to better evaluate gene expression changes upon siRNA treatment.
In the second section, a FA-functionalized, multivalent copolymer (FAPol13) was introduced to: (i) complex with siRNA to form a FAPol13/siRNA complex, (ii) protect siRNAs from enzymatic degradation, (iii) enhance cellular uptake by conjugating several FA molecules to copolymer, and (iv) increase RNAi efficacy eventually. A typical FAPol13 compound has three functional groups: cationic, hydrophilic, and FA moieties for providing siRNA packaging site, water solubility, and cell-selectivity, respectively. This nontoxic polymer successfully delivered siRNAs against Gluc, survivin (Sur), Caspase 8 associated protein 2 (Casp8ap2) genes in KB cells and efficiently reduced their expression (i.e., 62% and 68% downregulation from siSv and siGLuc treatments, respectively). Strikingly, treatment of KB cells with FAPol13/siCasp8ap2 significantly repressed cell growth and induced cells into apoptosis (24.5%, p = 0.01). Furthermore, a real-time imaging system, employing fluorescence approaches (time-lapse, z-stacking, and colocalization analysis), has been developed to evaluate siRNA binding, cellular uptake, and escape from compartments, respectively. In particular, Pearson’s correlation coefficient (PCC) was employed to quantify siRNA endosomal escape, one of the crucial steps of siRNA intracellular trafficking. This method was further applied to the analysis of siRNA delivery in HeLa (human cervical carcinoma) and SKOV3 (human ovary carcinoma).
In the third section, a gold nanoparticle (AuNP) capable of packaging and protecting siRNAs was utilized to transport siRNA to cancer cells. Cytotoxicity assay, cellular uptake, and gene down-regulation studies of the AuNP-siRNA system indicate that AuNP can be an efficient siRNA platform.
In the fourth section, a correlation between FR expression level and the delivering effectiveness of FA-conjugates was established by comparing cellular absorption, cellular uptake, and RNAi efficiency among KB, HeLa, SKOV3 and A549 (human lung carcinoma) cells.
Collectively, we have demonstrated effective FR-mediated and cancer cell-specific siRNA delivery by several approaches. Further studies may lead to the development of therapeutic siRNA delivery systems
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Interconnect optimizations for nanometer VLSI design
textAs the semiconductor technology scales into deeper sub-micron domain, billions of transistors can be used on a single system-on-chip (SOC) makes interconnection optimization more important roughly for two reasons. First, congestion, power, timing in routing and buffering requirements make inter- connection optimization more and more challenging. Second, gate delay get- ting shorter while the RC delay gets longer due to scaling. Study of interconnection construction and optimization algorithms in real industry flows and designs ends up with interesting findings. One used to be overlooked but very important and practical problem is how to utilize over- the-block routing resources intelligently. Routing over large IP blocks needs special attention as there is almost no way to insert buffers inside hard IP blocks, which can lead to unsolvable slew/timing violations. In current design flows we have seen, the routing resources over the IP blocks were either dealt as routing blockages leading to a significant waste, or simply treated in the same way as outside-the-block routing resources, which would violate the slew constraints and thus fail buffering. To handle that, this work proposes a novel buffering-aware over-the- block rectilinear Steiner minimum tree (BOB-RSMT) algorithm which helps reclaim the “wasted” over-the-block routing resources while meeting user-specified slew constraints. Proposed algorithm incrementally and efficiently migrates initial tree structures with buffering-awareness to meet slew constraints while minimizing wire-length. Moreover, due to the fact that timing optimization is important for the VLSI design, in this work, timing-driven over-the-block rectilinear Steiner tree (TOB-RST) is also studied to optimize critical paths. This proposed TOB-RST algorithm can be used in routing or post-routing stage to provide high-quality topologies to help close timing. Then a follow-up problem emerges: how to accomplish the whole routing with over-the-block routing resources used properly. Utilizing over-the- block routing resources could dramatically improve the routing solution, yet require special attention, since the slew, affected by different RC on different metal layers, must be constrained by buffering and is easily violated. Moreover, even of all nets are slew-legalized, the routing solution could still suffer from heavy congestion problem. A new global router, BOB-Router, is to solve the over-the-block global routing problem through minimizing overflows, wire-length and via count simultaneously without violating slew constraints. Based on my completed works, BOB-RSMT and BOB-Router tremendously improve the overall routing and buffering quality. Experimental results show that proposed over-the-block rectilinear Steiner tree construction and routing completely satisfies the slew constraints and significantly outperforms the obstacle-avoiding rectilinear Steiner tree construction and routing in terms of wire-length, via count and overflows.Electrical and Computer Engineerin
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